Apparatus for molding insulators



July 9, 1935. E. H. FlscHER 2,007,567

APPARATUS FOR MOLDING INSULATORS P11901 Nov. 21, 1934 2 sheets-sheet 1 l l WITNEssEs; INVENToR m at C." Eugene H. F/scher 1 vw ff f BY l f l m AT NEY E. H. FISCHER 2 Shets-Sheet 2 lNvvENToR ene H. Fischer- AT RNEY July v9, 1935.

APPARATUS FOR MOLDING yINSULAToRs Filed N Ov. 21, 1934 Patented July 9, 1935 APPARATUS Fon iuoLpiNe. INsULfroRsj. 'f 'f ,"Eugene HQ Fischer, Derry, Pa., assigner to Westf ing'house Electric &\Manufacturng Company, -East Pittsburgh,v Pa., a .corporationlof` Penn- 1` ISylvania pplication November 2 1, 1934Serial No. 'l5y4,ll5(i` y Y Claims. i My invention. relatesfto' improved apparatus for forming electrical insulators from plasticrna- `terial`,;and\more particularly, to adevice for mold,-

ing 'in asingle operation,`..by the hot-pressing4 5. method, faliorcelainA shell having an internalsur-` "surface of revolution in as simple. andcheap a manner aspossible. Experience has shown .that the useof thelapparatus Vdescribed in the present application fisan improvement.y over that. `dis-` closedinthe patent. n

` In practicing Illy-invention. .Il propose to employ two sup' erimposed mold sectionsv for :receiving Vthematerial tolbe molded and insertinto the recess'lrdei'lned .bysaicl sections a ,rotatabledie which .will forma symmetrical-recessin the mold material, .and at the, same time, force itinto `intimate Contact .with the innerfvvall 'of `the mold sections, at tleast one of .which has recessesther ein yfor.forxningalug.orfprojection on'the molded` insulator. Means are provided for ,maintaining the mold. sections in .axial alignment `andfor exerting a pressureon the upper` rnold section coincidentwith the insertion of the rotatable die tof maintain the mold sectionsin operative posi-v ,.t on. 3,

. Referring tothe drawings: .v j Figure `1 is ,a view,in vertical section, of the molding or hot-pressing apparatusembodying my.4

invention; g i Y Fig. 2 is a view in vertical section,` of an insulator ,formed'by the apparatus shownin Fig. 1`;

`Figs. 3 and 'i are section and top views, respec tively, of the rotatable' dieshovvninl Fig'. 1; MFigs- 5 and G are views, insection and ,top plan, respectivelyjof the upper mold section ofFig'. 1j Figs. 'l andl 8 are, respectively.,Yvievvs` in partial vertical section vancl'top plan `ofthe insulator.

blank from. which 'the finished 'insulator shown n in Fig. 2 is turned@A Figs. 9 rand -l0.are, respectively, vievvs in partial vertical section and top plan vievv ofthe lower, mold` section shown in Fig. l; and

Fig..- A11 is a fragmentary View in sectionof a detail ofthe upper mold section..

`- Referring more specifically .tothe '.dravving'si.A

(or 25a-3V and particularly, Fig. 1 thereof, the molding ap-.

paratus comprises a )moisture .absorbent lower mold, section VI offplaster of Paris, or the like, anV

upper mold section I 9, removably mountedthereu on, and arotating die 2t adapted to be insertedv into the-,recess defined by the sections` I `a-ndlli, to` deneqthe shape lof the resulting insulator.

blankishownin Figs. 7 and18),

The .lower moldsection I, shown more spe-vv cificallyfinFgs. 9=and.1 0., comprises ya rela-tively heavy body of plaster of Faris, vor the like, having a recess 21- therein corresponding'to the top porf4 tion. of the'insulator shown in Figy2. The upper face of thev mold section l; surrounding the mouth ofA thel recess 2, constitutes ga. plane bearing surface for-supporting lthefupper mold section, and

has` provided 4therein threey symmetrically dis-- posedsockets -3 VEach socketcomprises a short metallic Asleeve;'embedded in ,fthe mold.r material With'thelopen` end thereofsubstantiallyflush with the plane upper surface of the mold. In order to anchor "thesesleeves in position, lugs `fi may be soldered, Vbrazed, or otherwise' securedv thereto, extendngxinto the` material ofthe `mold section. The sleevesz andlugs-l are cast into the mold sec tionWhen -the latter is formed, and it is to be understood-that; other expedients may be employed to anchor the sleeves3 in position, or,r fact, to use othermeans than sleeves to provide a plurality of-sockets for receiving the pins I3.

Referring to Figs. '7 and 8,'the insulator blank to be formed has ailowerportion 5 which is symmetrical With respect to the'vertical axis of the insulator, and an upperiportion 6 corresponding inshape to the'recess inthe upper mold section.

IG, having formed thereon outstanding lugsA l.

Referring more specifically to Fig. 5, which is takenon the line V-V of Fig. 6, theupper mold section comprises a metalliccasting having a lower flange I2 proportioned to rest upon the plane upper surface of the lower 'moldsection I. Secured to the outer extremity ofthe flange I2 are `three pins i3, symmetrically disposed With respect to the axis of theinsulator, .andV proportioned to fit into the sockets 3 in the upper surfaceof the lovver insulator section I, to prevent.

relative l axial ,movement of lthe tvvomoldr sec. tions I and l0 when they, are in operative position,

' asshovvn-in Fig..1. Aring I4 is loosely secured to the castvbodyofthe upper section lil below the flange. I2, and, vvvhe`ny the two mold sections are together, lies Within the recess 2v ofjthe lower moldl-section, a's shown more clearly" in Fig.1.' Themeansfor securing the ring I dlrto the main section of the'mold'comprises-a plurality of bolts,

one of which is shown in Fig. 11, extending down through the main body I0 parallel to the axis thereof and tapped into the ring portion. The length of the bolts is such that when the mold section I0 is raised the ring I4 separates therefrom a limited amount, for a purpose hereinafter described.

Recesses I5 are provided within the body por-Y tion of the section I0 to accommodate suflicient of the molding material to form the lugs 1. The interior of the mold section I0, except for the recesses I 5, is a surface of revolution about the vertical axis of the section.

Four resiliently-mounted plungers I6 project from the upper face of the mold section, parallel to the vertical axis thereof, for a purpose hereinafter described. Each plunger comprises a hollow metallic rod slldably mounted in a socket II, in the wall of the mold section III, and is biased outwardly by means of a coil spring, as shown in detail in Fig. 5,

Two handles I8 may be bolted or otherwise suitably secured to the casting to facilitate handling thereof, as shown in Figs. 5 and 6.

Vents I9 are provided through the wall of the casting I0 communicating with the recesses I5 to permit the escape of air when pressure is" applied to the molding material, so that the molding material may completely fill the recesses. Similarly,

a plurality of vents are provided around the base of ange I2 communicating with the space between the ring I4 and the mold section I.

Referring to Figs. 3 and 4, the rotatable die 23 for insertion into the mold sections I and III comprises a head portion having a projecting tip 2I, suitably secured thereto, as by screw threads as shown in Fig. 3. The upper end of the head portionv is in threaded engagement with a powerdriven shaft 22, 'which may constitute part of a press of the type usually employed inhot-pressing work.

A cast ring 2-3 partially embraces a flange on the upper end of the head portion, and is maintained in position by a plate 24 suitably secured thereto,

as by bolts 25. The assembly comprising ring 23 and plate 24 is somewhat loose upon the flange, so

a suitable stationary member (not shown), to

prevent rotation of the assemblies 23 and 24 when the head isrotated by means of the shaft 22, and at the same time, permit the head with the shaft 22 to reciprocate vertically.

In using the structure thus far described, a quantity of plastic porcelain clay, or other dielectric material to be molded, sufficient to form the blank shown in Fig. '1, is placed in the lower mold section I. The upper mold section I0 is then placed in operative position with the pins I3 inserted in the sockets 3', so that relative axial movement of the two mold sections is prevented. n

The rotatable die 20 is then lowered, while it is rotating, into the upper end of sectionA I0 and asv facilitated by providing one or more flat areas on the head, or by having the surface of the head slightly eccentric with respect to the axis of rotation.

As the die descends, and before it reaches its lowest position, as in Fig. 1, the clay being forced upwardly into the upper mold section III, tends to cause the mold section I0 to rise out of its operative position on the mold section I. Upward movement is limited, however, by the plungers I6, which, as the die descends, are engaged by the under surface of the ring 23 to exert a pressure on the mold section II) to prevent separation 0f the mold sections by more than a slight amount. Before the rotating die descends to its lowest position, therefore, the mold section I0 floats slightly above the section I, but is guided in an axial direction by the pins I3 and sleeves 3, thereby permitting some of the plastic material to escape between the mold sections to insure that the space below ring I4 is completely filled.

By reason of the fact that the ring 23 does not rotate withV the head of the die, the only force applied tothe mold section In through the plungersv I3will be in a direction parallel to the axis of the die. Accordingly, there will be no tendency for the mold section I0 to rotate with respect to section I. y

The descending die continues its movement untilthe plungers I6 are completely depressed, and upon further movement of the die, the mold section Il is positively depressed to the position shown in Fig. l, the configuration ofthe die head and tip 2I determining the inner surface of the resulting insulator blank. As previously noted, duringthis operation air entrapped in the recesses I 5: in the mold section III may be permitted to escape through the vents I9, air accumulating adjacent to the top of the blank may escape through vents 29 formed in the head of the die (Figs. l and 3), and air may escape through the vents adjacent to the periphery of ring I4.`

It has been found in practice that with the apparatus described the resulting insulator blank is of uniform density and all depressions in the mold sections are completely filled. As the rotating die descends, the vflattened surfaces on it tend to beat the plastic mass, or clay, and force it outwardly against the side walls of the mold sections. At the same time the spreading action of the clay mass causes the mold section I0 to rise slightly against the force of the spring-plungers I6 so that some of the clay may escape between the sections. As the die descends there is an increasing resilient pressure on mold section I0, and as th'e die approaches its downward limit of movement, the mold section I0 is rammed positively into position to exert a substantial pressure on the clay, completely filling all parts of the mold and, in fact, causing some of it to escape through the various vents.

Upon completion of the operation described, the rotating die is withdrawn vertically and, in order to relieve the suction occasioned by such withdrawal to prevent marring vthe inner surface of the insulator, a check valve is provided in the' tip 2I. rlhis is shown in detail in Fig. l, as comf prising a valve head 30 seated in the lower extremity of the tip 2I, having a stem 3| and a spring 32 normally biasing the valve to closed position. As the die rises and a. condition of vacuum occurs adjacent the tip 2|, the valve 33 moves downwardly from the position shown in Fig. 1 to permit the entrance of air to break the vacuum. Ak suitable vent 33 is provided in the shaft 22 to facilitate this action.

to'r

fAfteriwit-hdrawal bf therotating die, the mold section logis removed, and` as; it is raised' the ring I4tseparates'sufficientlyrtopermit air to4 enter to break any vacuum that may exist adjacent -to the inner periphery, ofsthe 'ring` I4. v

When `the insulator blank has dried suic'iently topermit handling, it isremoved from the Amold section I `and mounted on a lathe andtrimmed to the shape shown-inl full lines inFig. y2.` Suitable holes 35, 36, 31 and 38 are drilled or punched for mounting the necessary hardware .and electrical fittings. to the insulator. The insulator is then.

red vand is ready `foruse. 1 l f kItshould be apparent from-theV foregoing defscription that the present` invention is ani improvement over the prior art in that it permits the forming of integral lugs onthe exterior surface of an' insulator coincident with the hot-pressing of .the bodyportion thereof. l, Itshould also be` apparent thatthe apparatus employed is simpler, both in structure and required manipulation,`

than thatshown inmyprior patent, above referred to. Quite obviously, however, modications may be made in the structure herein dissize or shape.

I claim as my invention:

1. Apparatus for molding insulators comprising a stationary mold `section having a recess corresponding to a portion of the exterior shape of the insulator and a plane upper Vsurface surrounding said recess, a second mold section of substantially cylindrical shape having an innerconflguration corresponding tothe remainder of the exterior shape of the insulator, means for maintaining said sections in superimposed axial alignment, a

rotatable die having a shape corresponding to the f inner shape of the insulator and means for moving it axially of said mold sections, and means operative upon movement of said die into the mold sections for pressing said sections together to maintain them in operative engagement.

2. Apparatus for molding insulators'compris` ing a stationary mold section rhaving a recess corresponding to a portion of the exterior shape of the insulator and a plane upper surface surrounding said recess, a second mold section of substantially cylindrical shape having an inner configuration corresponding to the remainderof the exterior shape of the insulator, means for maintaining said sections in superimposed axial alignment, a rotatable dier having a shape corresponding to the inner shape of the insulator and means for moving it axially of said mold sections, and cooperating means carried by said rotatable die and disposed on said upper mold section for pressing said mold sections together to maintain'them in operative engagement.

3. Apparatus for molding insulators comprising a stationary mold section having a recess corresponding to a porton of the exterior shape of the insulator and a plane upper surface surrounding said recess, a second-mold section of substantially cylindrical shape having an inner configuration correspon-ding to the remainder of the exterior shape of the insulator, means for maintaining said 'sections in' superimposed axial alignment, a rotatable ldie having a shape corresponding tok the inner shape of the insulator and means for carried `by ,saidV rotatable die and means -for preventing rotationthereof, and resilient means carried by the upper mold section disposed to be engaged by said ilangegfor exerting a resiilent pressure on saidrmold sections in a direction parallel to 'theaxes thereof upon movement of said die j into the mold sections.

4. A mold forforrning insulators comprising;-

two'.v stationary mold sections `in superimposed axial alignment defining a Arecess, correspon-ding tothe desiredexterior'rrshape of an insualtor, a rotatable die and means for-moving it axially of said stationary sections to form the inner surface of saidinsulator, and means carried-by said die for exerting a pressure on the rupper` of said mold sections in adirection parallel to the axis thereof tomaintain said sections rin Voperative relation as the die enters the mold sections.

5. A Vmold forforming insulators comprising relation as the die enters the mold sections, said means including a non-rotatable flange carried by sai-d die, and resilient means projecting from said upper mold section in a position to engage said flange.

6. Armold for forminginsulators comprising two stationary mold sections in superimposed axial alignment defining a recess corresponding to the desired exterior shape of an insulator, a rotatable die and means for moving it axially of said stationary sections to form the inner surface of said insulator, and means carried by said die for exerting a pressure on the upper of said mold sections in a direction parallel to the axis thereof to maintain said sections in operative relation as the die enters the mold sections, said means comprising a flange carried by said rotatable die, means for preventing rotation of said flan-ge, and aplurality of spring-biased plungers projecting above the upper face of the upper mold section in af position to engage said flange as the die descends into the mol-d'sections.

v7. rA mold for forming insulators comprising a lower stationary mold section of moisture absorbent material having a recess therein for receiving the molding material and .a vplane bearing surface surrounding said recess, an upper mold section of metallic material having a flange adapted to rest upon said plane bearing surface of the lower section and` having an opening therethrough in 'axial'alignment with said recess, a plurality of guide pins projecting from said flange, sockets in said plane bearing surface'for receiving said pins comprising metallic sleeves embedded in said lower section with the upper ends thereof substantially flush with said surface, and means below said surface for anchoring said sleeves in operative position.

8. A mold for forming insulators comprising a lower stationary mold section of moisture absorbent material having a recess therein for receiving the molding materialand a plane bearing surface surrounding said recess, an upper mold section of metallic` material having a ange adapted to rest upon said plane bearing surface of the lower section and having an opening theremoving :ii-axially ofjfsaid mold sections, a flange rthe Vmolding material into contact with the walls of such section, and means carried by said rotatable means for exerting pressure on said sections only in a direction parallel to the axis thereof. 15

9. Invcombination, two superimposed separable mold sections deiining a recess for the reception of material to be molded, means for maintaining said sections in axial alignment, a rotatable die proportioned to extend into said recess and havying av portion-thereof proportioned to close said recess when the die approaches its inner limit of travel, and means carried by said die for cooperation with the upper of said mold sections for eirerting a pressure thereon inthe direction of movement of the die to prevent separation oi.' the sections as the molding material is compressed.

10. Apparatus for molding insulators comprising a stationary mold section having a recess corresponding to a portion oi' the exterior shape ot the insulator and a, plane upper surface surrounding said recess, a second mold section of substantially cylindrical shape having an inner configuration corresponding to the remainder of the exterior shape of the insulator, means for maintaining said sections in superimposed axial alignment, a rotatable die having a shape corresponding to the inner shape of the insulator and means for moving it axially of said mold sections, and means operative upon movement of said die into the mold sections for pressing said sections with an increasing pressure as the die descends together to maintain them in operative engage- 20 

